一种双端排布热电堆结构设计与仿真优化

微机电系统(MEMS)红外热电堆是光谱仪、气体传感器、远程温度传感器等现代信息探测系统的核心工作器件,较高的表面利用率和响应度以及更简易的制备工艺将是未来该类器件制造技术的发展趋势。分别采用热偶条双端对称排布、取消红外吸收区、扩大冷端欧姆接触面积、支撑膜边缘开通绝热槽、充分发挥氮化硅钝化与红外吸收双功能作用等设计理念,对热偶条温差分布进行优化,研究热电堆性能的变化规律。采用ANSYS Workbench有限元分析软件对器件进行仿真发现：当传感器设计尺寸为1.5 mm×1.5 mm×0.3 mm,有效面积为1.21 mm²,绝热槽为1.1 mm×20μm时,双端开槽的热电堆探测器在具备更低制备成本的同时表现出最优性能。通过与普通双端热电堆性能进行仿真对比,发现绝热槽的引入使得探测器输出电压提升88.5%。这为未来温度传感器的设计制造提供了新颖的思路。     

功能-结构一体化NiCr/NiSi薄膜热电偶的制备

采用多层薄膜结构制备了NiCr/NiSi薄膜热电偶,该薄膜热电偶依次由Ni基超合金基片、NiCrAlY过渡层、Al2O3热氧化层、Al2O3绝缘层、NiCr/NiSi薄膜热电偶层以及Al2O3保护层构成.主要研究了热电偶层薄膜厚度和时效处理对热电偶性能的影响以及温度对Al2O3绝缘层绝缘性的影响.静态标定结果表明,热电...     

一种黑硅吸收层的热电堆红外探测器设计

设计一种以黑硅这种对几乎所以可见光和部分红外光具有很高吸收率的新型材料作为表面吸收层的热电堆红外探测器,针对这一设计作出了大量关于黑硅对不同波长下的红外吸收率的研究。通过红外基本理论,结合MEMS工艺的兼容性,设计采用两种热电偶材料叠放的方式,并以氧化硅薄膜作为隔离的结构;另外,探测器采用氧化硅上制作的多晶硅作为新型衬底。在器件释放中被XeF2正面腐蚀的部分是多晶硅,这样的设计解决了硅释放的对准问题和SOI衬底陈本高的问题。这种材料可以提高探测器的性能同时减小成本。     

30对薄膜热电堆

介绍了30对热电堆的结构及制造工艺过程、基体及基板材料的选择、堆座及堆帽的选用、主要技术性能,并对振动、湿热、高温、低温、稳定性、阻值变化、安放位置等性能测试作了具体说明。     

热电堆传感器及其应用

从热电偶测温的方法出发,闸述了热电堆传感器的原理。介绍了它在电测与非电测领域中的应用。     

基于悬浮吸收层的热电堆红外探测器结构设计

在这项工作中,设计一种新颖的热电堆红外探测器结构。该检测器利用悬浮吸收层-热电堆双层结构来实现高性能,同时具有相对小的尺寸。该双层结构的实现是通过引入两个分离的牺牲层,分别包括热电堆下方的多晶硅膜和其上方的聚酰亚胺沉积实现。尺寸优化后的仿真结果表明,该红外探测器的探测率、响应率和响应时间分别可以达到2.85e8 cmHz （ 1/2） / W, 1800 V / W和6毫秒。此外,本文提出热电堆红外探测器的制造方法是高度兼容于标准的CMOS工艺,这就使其高产量和低成本的生产成为可能。     

仪表工问答

12.辐射高温计的工作原理是什么?有哪些性能特点?答:辐射高温计包括辐射感温器、显示仪表和辅助装置三部分。辐射感温器则由透镜、热电堆、补偿系统及壳体等组成。工作时,由被测对象传来的辐射热能经透镜聚集在热电堆接受靶面上,热电堆所产生的电势信号就直接送显示仪表,中间无需电子线路。热电堆的接受靶面镀黑以提高黑度系数。WFT-202型辐射感温器的热电堆系用八对微细镍铬-考铜热电偶元件按星状排列串联组成。     

陶瓷薄膜热电偶研究进展

实时监测飞机发动机各部件表面工作温度对发动机安全监控及性能验证等有重要意义,随着第三代飞机发动机——陶瓷发动机的开发,陶瓷薄膜热电偶已成为研究热点.综述了陶瓷薄膜热电偶材料种类、制备工艺、热电性能、高温稳定性及其测试技术的研究现状,指出了陶瓷热电偶当前需要研究的问题.     

消耗式钨铼热电偶及其在炼钢测温中的应用

本文介绍能用于钢水测量的消耗式钨铼热电偶。它不仅能测2100℃的高温,而且可逐步替代铂铑系消耗式热电偶。实践证明,该热电偶有极为显著的经济效益。文中较详细地介绍了该装置的结构及其热电特性的标定等。     

基于电子印刷工艺的薄膜热电偶研制

薄膜热电偶由于具有体积小、热容量小及响应速度快等优点成为近年来学者们研究的重点。薄膜制备常用的方法有射频溅射法、离子镀膜法以及直流脉冲磁控溅射法等,但这些方法操作设备复杂,制作时间长,效率低,成功率低且复现性差。用电子印刷工艺制备薄膜热电偶,将Au,Pt的溶液化微纳米材料印制在基板上,印刷成为Au-Pt薄膜热电偶,该方法操作方便快捷,对电极材料污染小。通过试验证明:采用电子印刷工艺制备的Au-Pt薄膜热电偶符合Au-Pt热电偶检定规程的要求,热电偶精度高,重复性和一致性好。     

Thermal isolation of high-temperature superconducting thin filmsusing silicon wafer bonding and micromachining

Using a new micromachining technology, thermally isolated thin films of high-temperature superconductor have been microfabricated. The intended application for these structures is in infrared bolometers. A silicon wafer bonding process produces a low thermal mass island of single-crystal silicon on a silicon nitride membrane which provides thermal isolation. The silicon can act as a seed for the epitaxial growth of YBa₂Cu₃O₇ on a yttria-stabilized zirconia buffer layer. This paper describes the overall concept of the thermally isolated device, and demonstrates that the micromachined structure can be fabricated with high-quality superconducting films     

Calibration of residual stress difference of MetalMUMPs silicon nitride films

The metal multi-user MEMS processes (MetalMUMPs) provide one nickel film, two silicon nitride films and one polysilicon film for constructing various nickel MEMS devices. The two silicon nitride films are either bonded together as a bi-layered structure or they sandwich the polysilicon film to form a tri-layered structure to support nickel structures. The residual stress difference of the two silicon nitride films causes undesired deformations of suspended MetalMUMPs devices. In this paper, the residual stress difference of the two MetalMUMPs silicon nitride thin films is calibrated and the result is 169 MPa. The Young’s modulus of the MetalMUMPs nitride films is also measured, which is 209 GPa.     

Silicon nitride cantilevers with oxidation-sharpened silicon tips for atomic force microscopy

High-resolution atomic force microscopy (AFM) of soft or fragile samples requires a cantilever with a low spring constant and a sharp tip. We have developed a novel process for making such cantilevers from silicon nitride with oxidation-sharpened silicon tips. First, we made and sharpened silicon tips on a silicon wafer. Next, we deposited a thin film of silicon nitride over the tips and etched it to define nitride cantilevers and to remove it from the tips so that they protruded through the cantilevers. Finally, we etched from the back side to release the cantilevers by removing the silicon substrate. We characterized the resulting cantilevers by imaging them with a scanning electron microscope, by measuring their thermal noise spectra, and by using them to image a test sample in contact mode. A representative cantilever had a spring constant of /spl sim/0.06 N/m, and the tip had a radius of 9.2 nm and a cone angle of 36/spl deg/ over 3 /spl mu/m of tip length. These cantilevers are capable of higher resolution imaging than commercially available nitride cantilevers with oxidation-sharpened nitride tips, and they are especially useful for imaging large vertical features.     

Porous polycrystalline silicon: a new material for MEMS

A new technique for the fabrication of thin patterned layers of porous polycrystalline silicon (polysilicon) and surface micromachined structures is presented. First, a multilayer structure of polysilicon between two layers of low-stress silicon nitride is prepared on a wafer of silicon. Electrochemical anodization with an external cathode takes place in an RF solution. A window in the outer nitride layer provides contact between the polysilicon and the HF solution; the polysilicon layer contacts the substrate through openings in the lower silicon nitride layer (remote from the upper windows). Porous polysilicon growth in the lateral direction is found at rates as high as 15 μm min^-1 in 12M (25%, wgt) HF to be controlled by surface-reaction kinetics. A change in morphology occurs when either the anodic potential is raised or the HF concentration is decreased, causing the polysilicon to be electropolished. The etch front advances proportionally to the square root of time as expected for a mass-transport-controlled process. Similar behavior is observed in HF anodic reactions of single-crystal silicon. Dissolution of the polysilicon layer is confirmed using profilometry and scanning electron microscopy. Enclosed cavities (chambers surrounded by porous plugs) are formed by alternating between pore formation and uniform dissolution. Porous polysilicon also forms over a broad-area layer of polycrystalline silicon that has been deposited without overcoating the silicon wafer with a thin film of silicon nitride. The resulting porous layer may be useful for gas-absorption purposes in ultrasonic sensors     

PECVD 工艺中氮化硅薄膜龟裂研究

PE 氮化硅薄膜优异的物理、化学性能使其在半导体分立器件、IC 电路中常被用作绝缘层、钝化层而使用。然而,氮化硅龟裂问题是影响其作为钝化层使用的阻碍因素,因此,科学的氮化硅工艺条件对其薄膜质量的影响非常关键。给出了等离子体化学气相淀积（PECVD）氮化硅薄膜技术的原理,通过实验验证,确定了诱发氮化硅龟裂现象的原因,优化工艺条件,确定了 PECVD氮化硅的最佳工艺条件,杜绝了龟裂现象对氮化硅作为钝化层使用的影响。     

Microfabrication of submicron nozzles in silicon nitride

A novel microfabrication process is described for obtaining nanometer apertures in highly cusped nozzle-like structures fabricated in silicon nitride, having apex angles of up to a few degrees. The process is based on a sacrificial etch technology using single-crystal silicon as the mold and silicon nitride as the material for the nozzle. The nitride coating on the apex of the pyramid shaped mold is selectively etched off using a polymer layer as the etch mask, which leaves the tip of the silicon mold protruding from the masked nitride, thus defining the aperture of the nozzles. The silicon mold is then removed in an alkaline etchant, which leaves the freestanding nozzles. The process is applicable to fabrication of similar structures in a variety of other materials such as silicon dioxide, boron-doped silicon, polysilicon, and refractory and noble metals. The main requirement is the preferential etchability of the mold with respect to material for the nozzles     

Sealing of micromachined cavities using chemical vapor depositionmethods: characterization and optimization

This paper presents results of a systematic investigation to characterize the sealing of micromachined cavities using chemical vapor deposition (CVD) methods. We have designed and fabricated a large number and variety of surface-micromachined test structures with different etch-channel dimensions. Each cavity is then subjected to a number of sequential CVD deposition steps with incremental thickness until the cavity is successfully sealed. At etch deposition interval, the sealing status of every test structure is experimentally obtained and the percentage of structures that are sealed is recorded. Four CVD sealing materials have been incorporated in our studies: LPCVD silicon nitride, LPCVD polycrystalline silicon (polysilicon), LPCVD phosphosilicate glass (PSG), and PECVD silicon nitride. The minimum CVD deposition thickness that is required to successfully seal a microstructure is obtained for the first time. For a typical Type-1 test structure that has eight etch channels-each 10 μm long, 4 μm wide, and 0.42 μm tall-the minimum required thickness (normalized with respect to the height of etch channels) is 0.67 for LPCVD silicon nitride, 0.62 for LPCVD polysilicon, 4.5 for LPCVD PSG, and 5.2 for PECVD nitride. LPCVD silicon nitride and polysilicon are the most efficient sealing materials. Sealing results with respect to etch-channel dimensions (length and width) are evaluated (within the range of current design). When LPCVD silicon nitride is used as the sealing material, test structures with the longest (38 μm) and widest (16 μm) etch channels exhibit the highest probability of sealing. Cavities with a reduced number of etch channels seal more easily. For LPCVD PSG sealing, on the other hand, the sealing performance improves with decreasing width but is not affected by length of etch channels     

A self-aligned fabrication method of dual comb drive using multilayers SOI process for optical MEMS applications

A novel method for fabricating a self-aligned electrostatic dual comb drive using a multi-layer SOI process is developed. The present method utilizes four aligned masks, greatly simplify the existing SOI-MEMS fabrication methods in manufacturing optical MEMS devices. Here, the actuating structure consists of fixed combs and moving combs that are composed of single crystal silicon, nitride and polysilicon. One mask is used to provide a deep etching to etch polysilicon, nitride and single crystal silicon respectively. The nitride separates polysilicon and single crystal silicon and provides an additional dielectric for the purpose of producing bi- directional motion upon applying electrostatic forces. A dual comb drive actuator with optical structures was fabricated with the developed process. The actuator is capable of motion 250 nm downward and 480 nm upward with 30 V applied voltage at 4 kHz frequency. The dynamic characteristics of the first and the second resonant frequency of the dual comb-drive actuator are 10.5 kHz and 23 kHz respectively. Experimental results indicated that the measured data agreed well with simulation results using the ANSOFT Maxwell^® 2D field simulator, ANSYS^® and Coventor Ware^®.     

微型传感器中氮化硅薄膜的微加工技术

简要介绍了基于磁控射频溅射技术的Si3 N4 薄膜沉积技术及Si3 N4 薄膜基于剥离 (lift-off)技术的微加工技术。实验结果表明该技术适用于微型传感器及MEMS中绝缘薄膜的加工     

Mechanical property characterization of LPCVD silicon nitride thin films at cryogenic temperatures

T-shape, LPCVD silicon nitride cantilevers are fabricated to determine Young's modulus and fracture strength of silicon nitride thin films at room and cryogenic temperatures. A helium-cooled measurement setup is developed and installed inside a focused-ion-beam (FIB) system. A lead-zirconate-titanate (PZT) translator powered by a function generator and a dc voltage is utilized as an actuator, and a silicon diode is used as a temperature sensor in this setup. Resonant frequencies of identical cantilevers with different "milling masses" are measured to obtain thickness and Young's modulus of the silicon nitride thin films, while a bending test is performed to obtain fracture strength. From the experiment, the average Young's modulus of low-pressure chemical-vapor deposition (LPCVD) silicon nitride thin films varies from 260.5 GPa at room temperature (298 K) to 266.6 GPa at 30 K, and the average fracture strength ranges from 6.9 GPa at room temperature to 7.9 GPa at 30 K. The measurement setup and technique presented here can be used to characterize the mechanical properties of different MEMS materials at cryogenic temperatures.